Currently available single use cameras with flash illumination are provided with electronic flash. The electronic flash unit is relatively expensive, representing a significant portion on the overall cost of the camera, and requires a relatively large capacity battery for operation. Although the electronic flash unit may be recovered and recycled a number of times, thereby reducing the effective cost of the electronics, the battery is replaced each time the camera is re-manufactured to insure proper operation of the flash unit. It has been observed that an array of chemical flash lamps could be an attractive alternative to electronic flash in single use cameras and related applications.
U.S. Pat. No. 4,347,053 issued Aug. 31, 1982, to Fohl et al. discloses a flash illumination assembly having a plurality of electrically fired flash lamps located in a circular housing. The combustion products from the individual flash lamps are vented into a common central expansion chamber. The electronically fired flash lamps have the drawback of requiring a source of electricity such as a battery for ignition.
U.S. Pat. No. 3,751,656 issued Aug. 7, 1973, to Buckler et al. discloses percussively fired flash illumination devices that are formed of transparent sheet plastic, wherein a pair of opposed walls are marginally secured together to define a first cavity for retaining a combustible mixture. In one embodiment the pyrotechnic material is ignited by a primer body contained in a second cavity communicating with the first cavity by a small passage. The flash illumination device is fired by striking the primer through the wall of the second cavity with a firing pin which crushes the second cavity against an anvil to ignite the primer. Combustion products from the primer ignite the combustible mixture through the small passage. These flash illumination devices do not readily lend themselves to a compact array such as would be required for a single use camera.
U.S. Pat. No. 3,439,992 issued Apr. 22, 1969, to J. W. Shaffer et al. discloses a flash illumination device having a cup shaped base for containing the primer material and an anvil having passages for allowing the combustion products from the primer to ignite a combustible mass contained in a lamp envelope. The cup shaped base is sealed to the lamp envelope by crimping. Although these lamps could be formed into an array, the resulting structure is relatively complex, and therefore expensive to manufacture.
There is a need therefore for an improved percussively fired array of flash lamps.